Double Capacity MintyBoost with 4-AA Battery Holder Modification

Step 9 Extend the battery power leads

With the bottom of the battery holder facing up as in the first image below route the negative leads of both battery banks as shown. Don’t route the wires over the foam tape. Or if you don’t have foam tape on your holder (yet) leave room to add it. Don’t plan on placing form tape on top of the wires that you are routing now. The combined thickness of the foam tape and wires will make the battery holder sit up too high to fit into the Altoids tin. You’ll see why later. Strip and twist the ends of the two negative leads together but don’t solder yet.

Next add a length of (black) hook up wire to the joined negative battery leads and solder the connection as shown in the second image below. Then connect some red hook up wire to the positive lead of battery bank 2 and solder as shown. Make sure this wire is routed around the foam tape area and is long enough to meet up with the red lead for battery bank 1.

Finish this step by insulating the two solder connections indicated by the red and blue arrows in the second image. I used heat shrink tubing. Now as you can see in the third image below we have a battery holder with one common negative connection and two 3 volt positive connections.